meiosis eq: how is meiosis different from mitosis?

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MEIOSIS EQ: How is meiosis different from mitosis?

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Page 1: MEIOSIS EQ: How is meiosis different from mitosis?

MEIOSISEQ: How is meiosis different

from mitosis?

Page 2: MEIOSIS EQ: How is meiosis different from mitosis?

Chromosome

DNA

Gene

Page 3: MEIOSIS EQ: How is meiosis different from mitosis?

DIPLOID CELL= a cell with 2 of each kind of chromosome

_______________Chromosomes

Mom 1

Dad 1

“Homologous”

?

Page 4: MEIOSIS EQ: How is meiosis different from mitosis?

“Complete Set”__ Mom__ Dad

Dad 1

Mom 1

“__n”

“autosomes”

“sex chromosomes”

2

23

23

__Total46

Page 5: MEIOSIS EQ: How is meiosis different from mitosis?

Haploid Cell

= a cell with 1 of each kind of chromosome

Page 6: MEIOSIS EQ: How is meiosis different from mitosis?

“n”_____TotalChromosomes

23

or

Page 7: MEIOSIS EQ: How is meiosis different from mitosis?

“Gamete”(male/female)

Haploid + Haploid = ?n n 2n

“Zygote”

___ ___ ___

________

2323

23

23

23

The first cell is called a

Page 8: MEIOSIS EQ: How is meiosis different from mitosis?

WHY NOT ONLY MITOSIS?

• Mitosis produces an exact replica

Each parent would give a complete set of chromosomes(46)

Baby wouldn’t be Human

Page 9: MEIOSIS EQ: How is meiosis different from mitosis?

MEIOSIS= Sexual Cell Division Halving the chromosome #

Page 10: MEIOSIS EQ: How is meiosis different from mitosis?

1 Body Cell ?

Replicate DNA once and Divide?Twice

4 Eggs or 4 Sperm

Page 11: MEIOSIS EQ: How is meiosis different from mitosis?

1 Diploid (2n) 4 Haploid (n)

46 pairs

46 46

23 23 23 23

46

Page 12: MEIOSIS EQ: How is meiosis different from mitosis?

PHASES OF MEIOSIS

• Meiosis I

Interphase

PMAT I

• Meiosis II

PMAT II

Page 13: MEIOSIS EQ: How is meiosis different from mitosis?

FirstInterphase

Meiosis I

46

46 pairs

46 46

Page 14: MEIOSIS EQ: How is meiosis different from mitosis?

Meiosis II

= 4 Gametes

46 46

23 23 23 23

Page 15: MEIOSIS EQ: How is meiosis different from mitosis?

1 Diploid (2n) ?

46

92

46 46

23 23 23 23

Interphase

PMAT I

PMAT II

?

?

4 Haploid (n)

Page 16: MEIOSIS EQ: How is meiosis different from mitosis?
Page 17: MEIOSIS EQ: How is meiosis different from mitosis?

• Meiosis I occurs in four phases: prophase, metaphase, anaphase, and telophase.

Interphase?Chromosomes replicate Sister Chromatids

Centrosomes

Page 18: MEIOSIS EQ: How is meiosis different from mitosis?

• Prophase I =– the chromosomes condense and homologous chromosomes pair

up to form tetrads.

– At several sites the chromatids are crossed (chiasmata) and segments of the chromosomes are traded

(“crossing over”).

Page 19: MEIOSIS EQ: How is meiosis different from mitosis?

• Metaphase I = • the tetrads are all arranged at the metaphase plate.

• Anaphase I = the homologous chromosomes separate and are pulled toward opposite poles.

Page 20: MEIOSIS EQ: How is meiosis different from mitosis?

• Telophase I = – movement of homologous chromosomes continues

until there is a set at each pole.– Each chromosome consists of linked sister chromatids.

• Cytokinesis =usually occurs simultaneously.

• “NO further replication of chromosomes”

Page 21: MEIOSIS EQ: How is meiosis different from mitosis?

• Meiosis II is very similar to mitosis.Prophase II =

Page 22: MEIOSIS EQ: How is meiosis different from mitosis?

• Metaphase II =

• Anaphase II =

Page 23: MEIOSIS EQ: How is meiosis different from mitosis?

• Telophase II =

• Cytokinesis =

• End ?

four haploid daughter cells.

Page 24: MEIOSIS EQ: How is meiosis different from mitosis?

#? 46

#?#?

#?

46

23 each

92#?

Page 25: MEIOSIS EQ: How is meiosis different from mitosis?

Animation

Page 26: MEIOSIS EQ: How is meiosis different from mitosis?

P I M I

A I T I--------

4n

2n 2n

Interphase:ChromosomeDuplicate

Page 27: MEIOSIS EQ: How is meiosis different from mitosis?

P II M II

A II T II

- - - - - - - - - - - - - - - - -

-------

--------

-------

-------

- - - - - - - - - - - - - - - - -

n n

n n

Interphase:NoDuplication

Page 28: MEIOSIS EQ: How is meiosis different from mitosis?

Sperm (n) to Egg (n) = Zygote (2n)

Page 29: MEIOSIS EQ: How is meiosis different from mitosis?

• Fertilization restores the diploid condition by combining two haploid sets of chromosomes.

Page 30: MEIOSIS EQ: How is meiosis different from mitosis?
Page 31: MEIOSIS EQ: How is meiosis different from mitosis?

GENETIC VARIABILITYMeiosis “shuffles” genetic information

3 ways of “shuffling”

Page 32: MEIOSIS EQ: How is meiosis different from mitosis?

Dad

Mom

“Independent Assortment”

----

----

Page 33: MEIOSIS EQ: How is meiosis different from mitosis?

Human Gamete = 23n

– Egg: 223 = 8.4 million

– Sperm: 223 = 8.4 million

Egg + Sperm = 70 trillion possibilities

Page 34: MEIOSIS EQ: How is meiosis different from mitosis?

“Recombinant Chromosomes”

“Crossing Over”

Page 35: MEIOSIS EQ: How is meiosis different from mitosis?

“Random Fertilization”

200 – 500 million per ejaculation 1 egg

One “winner”

Page 36: MEIOSIS EQ: How is meiosis different from mitosis?

GENETIC VARIABILITY

Evolutionary adaptation?

Page 37: MEIOSIS EQ: How is meiosis different from mitosis?
Page 38: MEIOSIS EQ: How is meiosis different from mitosis?

THE CELL CYCLE, MITOSIS, and MEIOSIS

The Cell Cycle

2 Main PhasesTime Spent in eachWhat happens in all phasesStages of InterphaseChromosomes DNA Replication

Mitosis

Phases of MitosisCytokinesisChromosomes vs. ChromatidsChromosome NumberDiploidSomaticCancer

Meiosis

HaploidGametesPhases of MeiosisTetrads Crossing OverGenetic Variability